1. Field of the Invention
The present invention relates to an optical signal transmitting and receiving device, and particularly to a bi-directional transmitting and receiving device of light-splitting type.
2. Description of Prior Art
As shown in FIGS. 1 and 2, a bi-directional optical signal transmitting and receiving device 1 according to the prior art is mainly to combine an optical transmitter 11 and an optical receiver 12 within a T shape shell 10, one side of which is connected to an optical fiber 13, and other two sides of which respectively accommodate the optical transmitter 11 and the optical receiver 12, while there are two focusing lenses 15, 16 arranged on optical transmitting surface of optical transmitter 11 and optical receiving surface of optical receiver 12 respectively. A light splitting filter 14, fixed at the intersection of two beam paths formed among optical transmitter 11, optical receiver 12, and optical fiber 13, is inclined 45 degrees to two beam paths. One side of the light splitting filter 14 facing both optical receiver 12 and optical fiber 13 is coated with a reflecting coating, so that light beam coming from optical fiber 13 may be reflected downward to the optical receiver 12 by the reflecting coating of light splitting filter 14, while the light beam coming from optical transmitter 11 may pass through light splitting filter 14 and transmit directly into optical fiber 13.
There are many assembling aspects for the prior light splitting filter arranged in a shell to generate optical operational relationship for taking care the distribution of optical signal transmitting and receiving paths among optical transmitter, optical receiver, and optical receiver, such as U.S. Pat. Nos. 6,075,635, 5,841,562, 5,838,859, 5,408,559, 5,347,605, and 5,127,075, as well as Taiwan Patent Application No. 250458, 246900, 241892, 241891, and 588889, wherein the light splitting filter 14 is directly arranged at a fixative seat formed or arranged in the interior of shell.
The light splitting filter of bi-directional optical signal transmitting and receiving device disclosed by aforementioned prior arts is an individual component that must be fixed in the interior of shell through a particular positioning and packaging procedure, such that its manufacturing process is more sophisticated and accurate. As a consequence, its producing cost is higher and it is difficult to reduce the volume of shell, because the machining process for the light splitting filter must be more complicated and dedicated, as smaller the volume of shell is, less favorable for the positioning and machining of light splitting filter are.